Comments not shown on website but in forum

I got a strange problem and ran out of ideas.
Just updated WP t0 3.9.1 and WP-united to Version 0.9.2.8
Cross posting is working but not cross posting comments
(just with a trick)

If I post a comment on our website or in the forum they don’t show on the website just in the forum. Website only shows the number of comments.

My trick:
If I comment a news directly via the WordPress dashboard then it shows this comment on the website and all the other comments made.
But this WP dashboard comment is not showing in the forum (but every other comment is)

As soon as I delete this WP dashboard comment all the other comments are gone on the website as well (forum still showing them). I can only see the number of comments under the news post on the website but not the comments any more.

Maybe I missed something somewhere but atm I’m kinda lost as I don’t want to extra comment any news via the dashboard first.